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How can we
measure temperature?
The earliest
devices used to measure temperature were called thermoscopes. They
consisted of a big glass bulb with a long tube extending downwards
into a container of colored water or wine. Some of the air
in the bulb was expelled before placing it in the liquid, causing
the liquid to partially rise into the tube. As the remaining air
in the bulb was heated or cooled, the level of the liquid in the
tube would vary, reflecting the change in the air temperature. An
engraved scale on the tube provided a way of measuring the fluctuations.
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